An 85-kg person stands on a lightweight ladder, as shown in the figure(Rgurel).

Question

An 85-kg person stands on a lightweight ladder, as shown in the figure(Rgurel). The floor is rough; hence, it exerts both a normal force f1, and a frictional force f2, on the ladder. The wall, on the other hand, is frictionless; it exerts only a normal force Suppose the person climbs higher on the ladder. As a result, is the ladder more likely, less likely, or equally likely to slip? Choose the best explanation from among the following: The magnitude of must increase as the person moves upward. The forces are the same regardless of the person's position. more likely less likely equal likely When the person is higher, the ladder presses down harder on the floor. Consider the pulley-block system shown in the fiaure(Figure 1). Is the tension in the string on the left-hand rotating system greater than, less than, or equal to the weight of the mass attached to that string? Choose the best explanation from among the following: The string rotates the pulley in addition to supporting the mass. The mass accelerates downward. The mass is in free fall once it is released.

Explanation / Answer

So basically as you can see in the picture, there are no forces acting in the vertical direction except F1.
Therefore F1 is equal to the amount of force the floor is applying to the ladder, which is the combined weight of the both the ladder and the person. therefore :
F1 = 85kg * 9.81(gravity) + m * 9.81


Now as you can see the system is in static equilibrium. SO that means that F2 MUST be equal to F3(or the ladder would either fall through the wall

As stated before F2=F3

2)

Imagine that you have the arrangement of a 100 pound (45.4 kilogram) weight suspended from a rope, as shown here.

In this figure, if you are going to suspend the weight in the air then you have to apply an upward force of 100 pounds to the rope. If the rope is 100 feet (30.5 meters) long and you want to lift the weight up 100 feet, you have to pull in 100 feet of rope to do it. This is simple and obvious.

Now imagine that you add a pulley to the mix.

Does this change anything? Not really. The only thing that changes is the direction of the force you have to apply to lift the weight. You still have to apply 100 pounds of force to keep the weight suspended, and you still have to reel in 100 feet of rope in order to lift the weight 100 feet.

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